Three of the four suicide bombers who carried out the July 7 attacks on London were seen on a "reconnaissance mission" two weeks earlier, the Metropolitan police said today.

Detectives released new CCTV images of the men at Luton station and also at King's Cross station in London on June 28. The men were also pictured entering the underground system.

The trip followed the same route the suspects are believed to have taken on the day of the suicide bombings that killed 52 innocent people, police said.

Detectives found the images after discovering train tickets and receipts during searches of some the suicide bombers' homes. After analysing thousands of hours of CCTV footage, police concluded the men were on "an apparent reconnaissance mission to the capital".

"It is believed the visit on June 28 might suggest the suspects were carrying out reconnaissance of potential targets on the London transport system and checking the time of the journey they intended to take on the day of the attack," a police spokesman said. "Other cases here and abroad have suggested that terrorists do visit possible targets as part of their planning."

The images show Mohammad Sidique Khan, Shehzad Tanweer and Germaine Lindsay meeting at Luton train station around 8.10am. They bought tickets and shortly afterwards boarded a Thameslink train to King's Cross where they were captured on CCTV arriving and walking through the train station at approximately 8.55am.

The three men are then seen together again at Baker Street station at around midday, and then pictured back at King's Cross at 12.50pm. They then return to Luton on a Thameslink train, arriving at approximately 13.40pm.

Detectives are continuing to examine further footage to see if any other details about their movements on that day can be found.

Al-Qaida claims responsibility for 7/7 bomings

Last night, a video played on Arab television station al-Jazeera showed al-Qaida's deputy leader claiming the group was responsible for the London attacks.

Ayman al-Zawahri said the group had the "honour" of carrying out the bombings. It is the first time al-Qaida has claimed direct responsibility for the attacks. In previous statements, it simply blamed British foreign policy for the bombings.

The Metropolitan police had no immediate comment about the video.

The new report of a practice run for the bombings adds more weight to the theory that all four suicide bombers planned to detonate their rucksack bombs on the tube system. Three of the four bombers detonated their devices on underground trains while the fourth exploded his on a bus.

It is thought that the bus bomber, Hasib Hussain, was prevented from getting on the Northern Line on the day of the attacks because of disruption to the service.

The other bombers, Tanweer, Lindsay and the suspected ringleader, Sidique Khan, detonated their devices almost simultaneously.

Earlier this month, a video suicide message from Sidique Khan emerged in which he claimed that the British public were to blame for the terror attacks.

In the al-Qaida video released yesterday, Zawahri claimed the bombings were carried out to strike at "British arrogance".

"The London attack is one of the attacks that al-Qaida ... had the honour of carrying out against ... British arrogance, the aggression of the crusader British against the Muslim nation for over a hundred years," he said.

Osama bin Laden's deputy also criticised the elections in Afghanistan and said the US would not tolerate independent Islamic governments. He was shown wearing a black turban and a white robe, against a sackcloth background, often used by al-Qaida to disguise the location.

Families of the dead to receive £10,000 from charity

The families of those killed by the London bombings will receive payments of at least £10,000, a charity announced today.

The London Bombings Relief Charitable Fund (LBRCF) said that those seriously injured in the attacks could receive £15,000. Extra payments would also be made to help dependent children of the victims.

These grants top up the £10,000 payments already made to the bereaved and the £6,000 to the seriously injured to help meet immediate financial needs. The main source of compensation remains the government's criminal injuries compensation scheme.

But in the Guardian today, lawyers for the most severely injured victims said they could be left struggling financially for the rest of their lives because of the shortcomings of the scheme.

Some of the most badly hurt survivors told solicitors they are concerned about their financial future and are angry at the long delays they face - up to 15 months and more - before they receive any money.